The Golgi complex in mammalian cells fragments during mitosis and these fragments are segregated between the two daughter cells. The post- mitotic re-assembly of the Golgi involves two related membrane ATPases, p97 and NSF. While p97 is highly abundant and evolutionarily more ancient than NSF, comparatively little is known of its function. I propose to determine the substrates of this ATPase in post-mitotic Golgi re-assembly by analyzing the formation of Golgi SNARE complexes with p97 and it's co-factor, p47. Using this method as a starting point, the role of p97 in Golgi re-assembly will be investigated. Clues as to the function of p97 suggest that it's action on Golgi SNARES and/or other substrates may be regulated by the mitotic state of the cell and that it may play a role distinct from that of NSF by acting on different types of SNARE complexes. Also to be investigated is the hypothesis that p97 and NSF act on morphologically distinct regions of the Golgi membrane. Answers to these questions will provide new insights into the effect of the cell cycle on membrane dynamics and the molecular mechanisms of organelle assembly.